Analysis of the modifications in the spectral and morphologic regularity during ventricular fibrillation produced by physical exercise and the use of glibenclamide

Abstract

Chronic physical exercise modifies cardiac activity improving response to malignant arrhythmia and, specifically, ventricular fibrillation (VF). Drug administration as glibenclamide, responsible for K+ATP channel blocking, is also generating a positive response against fibrillation. This work shows an analysis of cardiac response differences between physical exercise and glibenclamide during VF, both under conditions of perfusion and ischemia. Isolated rabbit heart was used, acquiring epicardial mapping signals for sedentary, physically trained and sedentary with glibenclamide subject groups. Spectral and morphological regularity of VF signal were obtained. Two spectral parameters were assessed: dominant frequency (DF) and normalized energy (NE), together with the morphologic regularity index (RI). Regions of interest (ROI) were obtained to evaluate the spatial distribution of mentioned parameters and were also used to obtain two parameters, namely, ROIn as the number of electrodes in each region and ROIa as the most regular surface in the map. Results show that physically trained subjects show higher spectral and morphological regularity compared to sedentary subjects in perfusion (NE: 0.33±0.07 vs 0.30±0.06; ROIa_NE: 56.25±25.60 vs 47.53±24.62; RI: 0.84±0.05 vs 0.83±0.07; ROIa_IR: 40.14±25.97 vs 34.98±25.61) and ischemia (NE: 0.31±0.06 vs 0.30±0.06; ROIa_NE: 46.58±24.96 vs 45.18±25.00; RI: 0.85±0.05 vs 0.84±0.07; ROIa_IR: 30.10±20.05 vs 27.51±20.26). Those administered glibenclamide also show higher regularity values than sedentary in perfusion (NE: 0.32±0.06 vs 0.30±0.06; ROIa_NE: 55.75±23.98 vs 47.53±24.62; RI: 0.86±0.05 vs 0.83±0.07; ROIa_IR: 46.52±24.72 vs 34.98±25.61) and ischemia (NE: 0.36±0.06 vs 0.30±0.06; ROIa_NE: 66.85±20.02 vs 45.18±25.00; RI: 0.88±0.03 vs 0.84±0.07; ROIa_IR: 32.72±27.91 vs 27.51±20.26). We conclude that physical exercise and K+ATP channel blocking drug administration, both provide antiarrhythmic effects. However, there also exist differences in the cardiac response between physical exercise and drug administration groups.